Circulating miR-223-3p as an Independent Biomarker of Recurrent Thrombotic Risk After Ischemic Stroke

<b>Background:</b> Circulating microRNAs (miRNAs) have emerged as potential biomarkers of platelet reactivity and thrombotic risk. Among them, miR-223-3p regulates P2Y12 receptor expression and may influence response to antiplatelet therapy. This study aimed to evaluate the prognostic value of selected circulating miRNAs in post-stroke patients receiving antiplatelet treatment. <b>Methods:</b> Sixty ischemic stroke survivors were prospectively enrolled and followed for 18 months for recurrent vascular events (stroke, transient ischemic attack, or myocardial infarction). Plasma levels of miR-126-3p, miR-223-3p, miR-24-3p, and miR-199a-5p were quantified using reverse transcription real-time PCR. Clinical data, antiplatelet regimen, statin use, and Essen Stroke Risk Scores (ESRS) were recorded. Logistic regression was applied to identify independent predictors of thrombotic events. <b>Results:</b> Expression of all examined miRNAs differed significantly across treatment groups. The dual antiplatelet therapy (DAPT) group showed the highest levels of miR-126-3p and miR-199a-5p (<i>p</i> < 0.01). Within the statin-naïve DAPT subgroup, lower miR-199a-5p levels (<i>p</i> < 0.001) were observed among patients who experienced ischemic events (n = 7/60; 12%; stroke = 4, TIA = 2, ACS = 1) during 18 months of follow-up. In multivariate analysis, reduced miR-223-3p remained the only independent predictor of recurrent thrombotic events (OR 1.18, 95% CI 1.01-1.37, <i>p</i> = 0.036), independent of ESRS and platelet reactivity. Elevated miR-126-3p and miR-199a-5p were associated with favorable treatment response, particularly among statin users. <b>Conclusions:</b> This study identifies low circulating miR-223-3p as an independent biomarker of thrombotic risk in post-stroke patients, potentially reflecting enhanced platelet activation via P2Y12 signaling. In contrast, higher miR-126-3p and miR-199a-5p levels may indicate more effective antiplatelet response. These findings support the potential utility of miRNA profiling for individualized antiplatelet therapy and long-term risk stratification after ischemic stroke.